Triarylamine dimer derivative having amorphous phase

Abstract

A triarylamine dimer derivative is represented by the following chemical formula [1](in the chemical formula [1]: —Ar1, —Ar2, —Ar3 and —Ar4 are aryl groups being to have a substitutional group respectively, —R1 and —R2 are same or different to each other and one thereof is selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group and a halogen atom; m and n are from 0 to 4; and with a proviso that —Ar1 and —Ar2, —Ar3 and —Ar4 are being to bind respectively to compose a cyclic structure group having a nitrogen atom) having an amorphous phase indicated by spectrum of powder X-ray diffractometry. The triarylamine dimer derivative is used for a charge transport material, an electrophotographic photosensitive conductor having thereof, an electroluminescence elemental device having a hole transport material thereof

Description

BACKGROUND OF THE INVENTION [0002] This invention relates to a useful triarylamine dimer derivative having amorphous phase (non-crystal phase) for a charge transport material of an electrophotographic photosensitive conductor and a hole transport material of an electroluminescence elemental device, its manufacturing method, and organic semiconductors that applies them. [0003] With regard to the organic electrophotographic photosensitive conductor, the organic semiconductor such as the layer-built electrophotographic photosensitive conductor is widely used. [0004] The layer-built electrophotographic photosensitive conductor is laminated with a charge generation layer including a charge generation material such as phthalocyanine-type compound that generates the charge by irradiation of light and a charge transport layer including a charge transport material that transports the charge to a surface of the conductor. [0005] Various solid solutions, that the charge transport material is d...

AI Technical Summary

Benefits of technology

[0023] It is an object of the present invention to provide a triarylamine dimer derivative without a introduced long substitutional aliphatic group, that has sufficient solubility into the organic solvent, excellent sensitivity and amorphous phase, and forms a thin charge transport layer by a simple coating method such as a dipping method or a spin-coating method, and a manufacturing method thereof.

[0026] It is found that a specific triarylamine dimer derivative having amorphous phase as crystal transformation has very sufficient solubility, excellent solute stability, an excellent formation property of the layer on the occasion of using for a charge transport material of a photosensitive conductor, an excellent photosensitive property such as dark decrement. Further it is found that the triarylamine dimer derivative is used for the organic semiconductor such as the electrophotographic photosensitive conductor, the hole transport material, the organic electroluminescence elemental device.

[0043] It is preferable that the heating and fusing steps are executed under reduced pressure or nitrogen atmosphere for preventing thermal decomposition thereof.

[0049] The organic solvent and the poor solubility solvent are not to be construed to limit the above-mentioned solvents. The organic solvent may be the other solvent that can dissolve the solid of the triarylamine dimer derivative efficiently. The poor solubility solvent may be the other solvent that can re-precipitate the triarylamine dimer derivative efficiently.

[0056] As explained above, the triarylamine dimer derivative having the amorphous phase has the more excellent solubility than the derivative having the crystal phase into the organic solvent such as tetrahydrofuran (THF), dimethyl formamide (DMF), xylene, chloroform, dichloromethane. Above all, N,N′-diphenyl-N,N′-bis(2-naphthyl)-4,4′-diaminobiphenyl has the further more excellent solubility and solute stability than alpha-NPD as structural isomer thereof and TPD as the usual charge transport material.

Problems solved by technology

If the charge transport material precipitates to be hardly uniform on the occasion of forming thereof, it causes white hole fogginess on the occasion of printing.

It is difficult to form the layer thereof because of its very low solubility into a solvent or a resin.

Therefore, alpha-NPD as the charge transport material is not put into a practical use in a field of the electrophotographic photosensitive conductor that is formed by applying of the layer as a general procedure.

However TPD often causes problems of the insufficient solubility or the crystallization on the occasion of forming the layer as the sensitive conductor onto a drum.

These derivatives cause still the insufficient solubility into the organic solvent, or the crystallization on the occasion of forming the layer as the sensitive conductor onto the drum.

Therefore these derivatives cause the problem that the charge transport layer becomes hardly uniform.

And the triarylamine dimer derivative cannot acquire the sufficient properties on the occasion of using for the charge transport layer of the electrophotographic photosensitive conductor.

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